borsboom/current-atlas-tables

Scripts to generate lookup tables for the the Current Atlas: Juan de Fuca Strait to Strait of Georgia

current-atlas-tables's Issues

Hello from some Gulf Island sailors.

My wife and I are sailing up through the Gulf Islands right now (Saturna at the moment - https://stephaniecp.github.io/ahoy/). Can we buy you a drink to thank you for the current tables? We've done some coding work with the Current Atlas also.

Thanks!

Jon and Steph

Readability Enhancement Request

Hi

In planning our club paddles, I print off a copy of your Current Atlas Lookup Tables for the year.
Then, I use highlighting pens to mark up the tables, based upon whether currents will be strong, moderate or light.
For example, pages 1 through 8 indicate a strong flood, so I would mark these up with pink.
Pages 9 through 15 are moderate, so I would mark these up with yellow.
Pages 16 through 21 are light, so I would mark these up with green.
And similar with the ebb pages.

Doing this takes some time, but I end up with a much more visual indication of when to plan our paddles, and what to expect from currents.

In your calculate.py code, you initialize data for each of the pages as follows:

flood_30_info = { 'pages' : [1,2,3,4,5,6,7,8],
'cycles': 1.0259 }
flood_18_info = { 'pages' : [9,10,11,12,13,14,15],
'cycles': 1.0516 }
flood_06_info = { 'pages' : [16,17,18,19,20,21],
'cycles': 1.0558 }
ebb_30_info = { 'pages' : [22,23,24,25,26,27,28,29],
'cycles': 1.0576 }
ebb_18_info = { 'pages' : [30,31,32,33,34,35,36] ,
'cycles': 1.0174 }
ebb_12_info = { 'pages' : [37,38,39,40,41,42,43] ,
'cycles': 1.1756 }

This seems to be a good place to add a background colour during initialization.
Then propagate it later during HTML formatting in format.py.

Python is not my strongest skill. I imagine I would spend many hours trying to get this working.

If you are entertaining enhancements, I would like to ask that you create HTML output with pink/yellow/green background behind each of the page numbers as described.

Kind regards
Gary

Current atlas tables beyond 2020

Any chance you will be posting Current Atlas Tables beyond 2020? My group of sea kayakers in Bellingham find your tables extremely valuable and appreciate you making them available.

Possible issue with 2021 tables

I couldn't find another way to contact you so I am logging an issue here.

I'm the developer of the PNW Current Atlas (an app that uses officially licensed data from CHS to present the Current Atlas on mobile devices). As the developer I too have had to work out the calculations. One different for me is, I get the reference tides directly from a feed at CHS (and in higher resolution than is publicly available, not that resolution really matters here).

I think you have a problem with your 2021 tables, particularly with July 2nd (but likely other dates as well). As you know, the chart 'cycles' synchronize with the Hi/Lo times at Point Atkinson. For July 2nd, according to CHS, the Point Atkinson tides are (corrected for PDT, using this public data: https://tides.gc.ca/eng/data/table/2021/wlev_ref/7795):

2 | 12:25 AM  | 4.5
2 | 07:37 AM  | 2.2
2 | 01:18 PM  | 3.2
2 | 06:11 PM  | 2.5
3 | 12:57 AM  | 4.3

So we'd expect the current atlas chart cycles to start on those time. However, in your tables for July you have this:

Inferring, you have chart cycles starting on:

2 | 01:04 AM  | 2.2
2 | 08:42 AM  | 3.2
2 | 03:13 PM  | 2.5
2 | 07:31 PM  | 2.5

This is where I believe you have a problem - your chart cycles in your tables do not line up with the official CHS reference station Hi/Lo times. But the problem you have is not evenly distributed in your tables as if you go back to January 1st, your tables are correct (aside from being off a few minutes from not using official CHS tide times).

I suspect that whatever you are using for source reference data is not correct and causing your tables to be wrong. Curiously, wagoner/washburns also have similar errors. OR, your logic that you use to skip charts to fit an hourly table is not working right (you skip charts 8, 43, 16, 21, and 22 - but I don't think this fully explains why you are so poorly synchronized with the CHS times on this date)

Fee free to reach out to me if you need further information, either here or directly: [email protected]